Manually activated pre-filled cartridges are commercially available from a variety of manufacturers, including the owner and assignee of the present invention. The owner and assignee of the present invention has developed a syringe which offers a unique and elegant integrated mechanism for retraction of the needle and/or syringe. Currently visual, tactile or audible indicators are generally linked to the end of stroke or some other mechanical mechanism and not to the end of dose. The integrated needle retraction syringe retracts the needle into the barrel, removing it from the patient's skin, once the dose is complete.
Pre-filled cartridges are used in the administration of drug solutions, drug suspensions, vaccines, medicinal therapies, and any other liquid medicament by parenteral injection. Such pre-filled cartridges include a primary drug chamber, a hypodermic needle permanently affixed to and in fluid communication with the drug chamber, and a piston slidably received in the drug chamber. The pistons of the pre-filled cartridges often include a plunger sub-assembly, which may include a plunger inner and a plunger outer, to force the liquid medicament from the needle. Pre-filled cartridges are typically prepared by pharmaceutical companies or sterile filling contractors in a sterile filling room in which the drug and the cartridge are brought together in a sterile manufacturing environment wherein all components and drug solutions are isolated from microbial contamination.
In contrast to manually activated pre-filled cartridges, automatic injection devices, commonly known as “auto-injectors,” are also available. Such auto-injectors, once triggered by the user, use an automatic mechanism to insert a hypodermic needle into the recipient's flesh at the injection site and force the liquid medicament out of a medicine compartment, through the hypodermic needle, and into the recipient. In addition to automatic needle insertion and dose delivery, some auto-injectors also incorporate retraction mechanisms to automatically retract the needle after use. Auto-injectors have proven particularly useful in allowing the medically untrained user to administer a parenteral injection, and can provide both psychological and physical advantages to patients.
Patients needing to inject medication for chronic disease management have used auto-injectors since the first reusable auto-injector was introduced in the 1990s. An auto-injector provides protection for the primary container, generally a pre-filled syringe, and offers an easy way for automatic injection of medication. These devices offer increased convenience and autonomy for patients as well as providing a competitive advantage to the pharmaceutical partner through device differentiation and increased sales through compliance of the patient to their therapy. Auto-injectors may also be beneficial in delivering large volumes (up to 1 mL currently) and viscous drugs. Auto-injectors also work to prevent needle stick injuries by housing the needle within a chamber, inserting the needle into the patient for drug introduction, then retracting the needle back into the housing utilizing, for example, reverse drive mechanisms.
Some auto-injectors have been designed to accept commercially available, manually activated pre-filled cartridges. Such configurations may be made in the form of cartridges for auto-injectors (e.g., reusable auto-injectors) or single-use auto-injectors. The syringes developed and manufactured by the owner and assignee of the present invention offer unique and elegant integrated retraction mechanism for needle safety. A number of different pre-filled syringes and cartridge configurations may be utilized in such auto-injectors, including those sold by the assignee and owner of the present invention under the trade name “Unifill” and covered by one or more of the following: U.S. Pat. Nos. 6,083,199, 7,500,967, 8,021,333, 8,002,745, 8,114,050, 8,052,654, 7,935,087, and 8,167,937; U.S. Patent Pub. No. 2011/0015572; and International PCT App. Nos. PCT/AU2010/001505, PCT/AU2010/001677, and PCT/AU2011/000515, all of which are incorporated herein by reference, in their entirety, for all purposes.